In the projector for projecting an image, there are proposed various types of projectors provided with a function (an automatic adjustment function) of detecting installation conditions (e.g., a distance from a screen, the tilt of the projector), and performing a focus adjustment and an adjustment of projection conditions such as keystone distortion correction in accordance with the result of the detection. In such a projector as described above it is arranged that the automatic adjustment function starts when the user performs a predetermined operation.
In contrast, the projector described in Japanese Patent Publication No. 2003-133118 is provided with a motion detection sensor for detecting whether the projector is in a moving state or in a resting state, and is arranged so that the autofocus function automatically starts when the operation of adjusting the position of the projector, for example, is completed and the projector becomes in a resting state. In other words, according to the projector described in the document mentioned above, since it is not required to perform the operation for activating the autofocus function, convenience of the users is enhanced.
However, projectors contain elements generating vibrations such as cooling fans or speakers inside, and the vibration varies in accordance with, for example, the rotational speed of the fan or the volume of a sound produced by the speaker. Therefore, depending on the operation state of the fan or the speaker, the vibration thus generated might have influence on the determination between the moving state and the resting state, and might incur false detection.